Packets and packet data systems are known and find numerous uses. Packet data systems allow for the transportation of packets to facilitate the transfer of information. For example, packets and packet data systems are used in cellular systems to send voice and data information to cellular phone users. Transporting information in today's world is accomplished by encapsulating specific types of information into packets and sending the packets through a “pipe.” A packet is a collection of information (i.e., data, voice, ET3, audio, etc.) The information contained in the package can be a combination of the aforementioned information types. When sending packets through a packet pipe, and more particularly a shared packet pipe, the packets are assigned a priority level. The priority level is assigned primarily based upon the size of the packet and the type of information contained within the packet. Certain packet types are time critical for transmission (full-duplex voice) and cannot be held up by currently transmitting non-time critical packets. When using a network comprising a shared packet pipe to transport information packets, it is common that large low priority packets clog the shared packet pipe leaving high priority packets waiting for the low priority packets to finish. The net result is an unacceptable delay in high priority transmissions.
Several prior art methods were devised to eliminate the clogging problem found in shared packet pipes. For example, preemption was previously included in the frame relay standard. Preemption is a method of stopping packets from traveling through a type of transmission line. For example, preemption occurs where a HDLC (High Level Data Link Control) protocol uses a “kill sequence” to end packet transmission. The “kill sequence” is a special sequence of bits issued by the packet transmission station. Both of these methods, while reducing delay, add to the bandwidth necessary to transport the packets because the transmitter has to retransmit the portion of the packet that was killed. Thus, a more effective method for transporting packets of varying priorities in a shared packet pipe transportation system is needed.